intel: improve command decoding

Decode both batch and state buffers.  Decoding is enabled with
INTEL_DEBUG=batch for now.  The functionality should be moved to the debug
layer in the future.
diff --git a/icd/intel/CMakeLists.txt b/icd/intel/CMakeLists.txt
index d64d8d4..434b115 100644
--- a/icd/intel/CMakeLists.txt
+++ b/icd/intel/CMakeLists.txt
@@ -19,6 +19,7 @@
 
 SET(SOURCES 
     cmd.c
+    cmd_decode.c
     cmd_mi.c
     cmd_prepare.c
     cmd_pipeline.c